Now I'm wondering if a hike along the pipeline (to Portland going south or to Montreal going north) is possible. Sounds interesting. There's a lot of history in this pipeline. Below is a very crude map, provided by PMPL, of the route the pipeline takes:

Hi, I came across your article and tought you might be interested to know that canadian Govt. and petrolum producers plan to reverse the flow of that pipeline to send Alberta's tar sands oil to Portland.

Here is a Facebook group about it (french only) http://www.facebook.com/group.php?gid=297141767267

My grandfather worked at both the Lancaster and Shelburne, NH pump stations. I think a hike would be possible. Much of the right of way is at least somewhat cleared. Snowmobilers use it a lot in the winter.